1. Field of the Invention
The invention relates to reciprocable fluid motors and more particularly to such motors which, for one reason or another, require the use of electrical power in conjunction with their operation. Examples of such uses are for welding guns and for sensing devices where it is desired to have some definite signal when positive contact is made by a reciprocable motor.
2. Description of the Prior Art
It is known to carry current in the needles of seam welder rollers. In such cases ionization sets up a plating effect which has a deleterious affect on bearing size.
A search of the prior art revealed the following pertinent U.S. patents:
Strickland U.S. Pat. No. 2,318,024: This patent shows adjustable contact blocks forming a split sleeve carrying current to a piston rod for a welding apparatus.
Dicks et al U.S. Pat. No. 3,538,294 discloses split fingers forming part of a piston rod which are spread into electrical contact with a cylinder surface in a welding device.
Tarbox U.S. Pat. No. 2,004,620 shows a welding tool in which the current passes through the cylinder directly to the piston.
Harris U.S. Pat. No. 2,293,338 shows another welding apparatus in which the cylinder and a split piston form part of the circuit.
Kane et al U.S. Pat. No. 2,863,983 shows an arc welding torch in which a split collet is carried by the piston and stationarily grips the electrode during operation.
These patents fail to achieve the objects of compactness, efficiency, facility for cooling, reduction of power consumption and others set forth below.